Purification and separation of carbon nanocapsules as a magnetic carrier for drug delivery systems

Nanoparticles of iron carbides wrapped in multilayered graphitic sheets (carbon nanocapsules) were synthesized by electric plasma discharge in an ultrasonic cavitation field in liquid ethanol. The as-prepared material contained carbon nanocapsules but also included impurities such as amorphous carbon, graphite balls and flakes. These impurities must be removed to allow the development of applications for the carbon nanocapsules and, it is necessary to develop a suitable purification method to obtain samples of monodispersed carbon nanocapsules. Two purification methods were used. The first used a hydrogen peroxide solution and acid etching to remove the amorphous carbon and iron particles. These impurities were easily oxidized and dissolved in the solution and the graphite layers of the carbon nanocapsules were not damaged. The second used magnetic separation using permanent magnets to remove the graphite balls and flakes. Here, centrifugation was applied to separate the purified carbon nanocapsules around 100–200 nm in size.     

Furfural Oxidation with Hydrogen Peroxide Over ZSM-5 Based Micro-Mesoporous Aluminosilicates

Micro-mesoporous aluminosilicates based on ZSM-5 zeolite, obtained by a dual template method, as well as in the presence of a dual-functional template (i.e. a Gemini-type surfactant), were tested in the oxidation of furfural with hydrogen peroxide. Even substantial changes in acidity and porosity of the catalysts result in minor variations of selectivity towards the desired products. Application of the synthesized zeolite-based materials in the oxidation of furfural with hydrogen peroxide leads to formation of 2(5H)-furanone (yield up to 28.5%) and succinic acid (up to 19.5%) as the main C4 reaction products. The kinetic model developed previously to treat the results for oxidation of furfural over sulfated zirconia was able to describe the data also for micro-mesoporous aluminosilicates.

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Morphological features of porous silicon carbide obtained via a carbothermal method

Samples of porous silicon carbide were obtained using sucrose or carbon and aerosil or silica mesoporous molecular sieves (SBA‐3, SBA‐15, KIT‐6 and MCF). Fibers content in silicon carbide samples is higher when the mesopore surface area of carbon materials derived from carbon‐silica composites is lower. Based on the found correlation between the morphology and porosity of SiC and mesopore surface area of the carbon component in the composites, a templating action of carbon in carbothermal reduction was suggested.     

MXene-containing composite electrodes for hydrogen evolution: Material design aspects and approaches for electrode fabrication

This work explores the possibilities for the processing of Ni- and Ti₃C₂T_x (T = OH, O) MXene-containing composite electrodes, by co-pressing and plastic deformation or by etching of the electrodes prepared directly by self-propagation high-temperature synthesis (SHS). Various material design approaches were also explored. In order to tune the Ti₃C₂ interlayer distance in Ti₃C₂Al MAX phase, an introduction of additional Al to form Ti₃C₂Al_z materials with z > 1 was attempted. Self-propagation high-temperature synthesis of powder mixtures with extra Ni and Al content (e.g. Ni:Ti:Al:C = 1:2:3:1) resulted in SHS products containing Ti₃C₂Al_z z > 1 material and Ni–Al alloys. Further etching of these products in 10M NaOH allowed the direct formation of electrodes with active surface containing Ti₃C₂T_x (T = OH, O) MXene- and Raney nickel-containing composites. The electrochemical studies were focused on hydrogen evolution and showed the potential for boosting the electrochemical reaction in Ni and MXene-containing composite electrodes, especially at high current densities. The guidelines for the processing of such electrodes under fluorine-free conditions are proposed and discussed.     

Iron-included carbon nanocapsules coated with biocompatible poly(ethylene glycol) shells

Nanoparticles of iron carbides wrapped in multilayered graphitic sheets (carbon nanocapsules) were synthesized by electric plasma discharge in an ultrasonic cavitation field in liquid ethanol and purified by selective oxidation and magnetic separation. The particles had 100–200 nm in diameter after centrifuging for 10 min at 4000 rpm. Carbon nanocapsules were covered by wispy poly(ethylene glycol) PEG coating about 7–10 nm in thickness. The number of PEG chains coated on carbon nanocapsules could be estimated as 9.15%. The values of saturation magnetization Ms and coercivity Hc of purified carbon nanocapsules without PEG coating were 112 emu g⁻¹ and 75 Oe respectively. Magnetically soft carbon nanocapsules with a poly(ethylene glycol) coating on the surface may possibly be used as biocompatible magnetic nanoparticles in medical applications.